(1) Field of the Invention
The present invention relates generally to manufacturing of head windows for submarines and more particularly to a fixture utilized during manufacture of the head window.
(2) Description of the Prior Art
During manufacture of a head window for a submarine periscope system, a critical thickness space should be established between the glass window and the wall of a frame for the glass window. The critical thickness space forms a gap that cushions the head window against sea pressures. Uniform thickness of the critical thickness space is essential.
The following U.S. patents describe various prior art fixtures.
U.S. Pat. No. 3,652,146, issued Mar. 28, 1962, to D. S. George, provides a precision stage assembly for an optical microscope which comprises an outer frame adapted to be rigidly mounted on the main structure of an optical microscope, an inner frame for carrying an X and Y traverse device on which a specimen may be carried, an intermediate frame between the inner and outer frames adjustable relative to the outer frame by a coarse focus drive, and releasable clamping means for rigidly clamping together the intermediate and outer frames, the inner frame being adjustable relative to the intermediate frame by a fine focus control mechanism and the inner frame being located with reference to the intermediate frame such that significant relative movement therebetween is restricted to movement in a vertical direction. The George reference concerns specific application of controlled two axis movement of a stage of a microscope. The third axis is that of the microscope itself. The cited reference does not discuss any kind of process of forming a cushion.
U.S. Pat. No. 4,880,349, issued Nov. 14, 1989, to D. A. Woodward, discloses a ceramic substrate held in position, while being processed, by vacuum. The substrate is positioned on an intermediate plate and held down by a vacuum. The intermediate plate is supported on an air bearing while being moved into correct location on a support member, after which the intermediate plate is held in position by a vacuum. The locating of the intermediate plate can be caused to move into position during movement of the support member to a processing position. As such, the cited reference uses vacuum technology and air bearings to support and position ceramic substrates. The reference does not discuss the means by which positioning is controlled, nor a process for use and fabrication of a cushion.
U.S. Pat. No. 5,280,894, issued Jan. 25, 1994, to Witcraft et al., discloses a fixture which includes a lower base for supporting and protecting the front surface of a semiconductor wafer and a clamp. The lower base has an upper end having a central surface portion recessed from a peripheral surface portion for supporting by means of an O ring the peripheral portion of the front surface of the wafer. The clamp rests on a peripheral portion of the back surface of the wafer with the remaining back surface exposed to the backside etching process. A pin and hole arrangement help align the clamp to the base. Holes in the base equalize pressure on both sides of the wafer.
U.S. Pat. No. 5,400,674, issued Mar. 28, 1994, to Arnone et al., discloses a precision component mounting and positioning apparatus with a frame member and a stage member suspended in the frame member. The frame member is adapted to be mounted on a support surface, and the stage member is adapted to receive a precision component, typically a precision optical component such as an optical fiber or waveguide. The stage member can be positionally adjusted relative to the frame member in five degrees of freedom. Three axially oriented actuators are grounded in the frame member to provide for selectively rotating the stage member about two orthogonally disposed transverse axes relative to the frame member as well as for axially translating the stage member relative to the frame member. A pair of orthogonally opposed transverse actuators are grounded in the frame member and oriented to provide for transverse translation of the stage member relative to the frame member.
U.S. Pat. No. 5,513,594, issued May 7, 1996, to McClanahan et al., discloses an apparatus for releasably clamping a substrate to a support platform, or other support system, at a face of the substrate. In one embodiment, a retractable clamp holds a substrate near its edges on a support platform when the clamp is in its fully extended position. One or more leaf springs are mounted to the clamp and apply force to the substrate at respective points in the event the substrate adheres to the clamp, thereby releasing the substrate from the clamp. In a preferred embodiment of the present invention, one or more activators are positioned in cooperative relationship to the leaf springs to cause the leaf springs to retract into recesses in the clamp when the clamp is extended against the substrate. In their retracted position, the leaf springs do not contact the substrate so as to minimize the generation of particle contamination and the chance of the release leaf springs themselves adhering to the substrate. As such, the cited reference does not contain any position control devices nor does the reference discuss a process of use and application.
U.S. Pat. No. 6,231,038, issued May 15, 2001, to Keyser et al., discloses a clamp ring assembly for securing a generally circular workpiece to a supporting surface with an annular base ring having a radial inner surface of a predetermined diameter and at least one locking member. The base ring further includes at least one opening extending axially therethrough for securing the base ring to the supporting surface. An annular securing ring having a radial outer surface and a radial inner surface is provided. The diameter of the outer surface of the securing ring is the same as or slightly smaller than the diameter of the inner surface of the base ring and the securing ring includes at least one locking member for engaging the locking member of the base ring when the securing ring is assembled with the base ring. The securing ring also includes at least one workpiece engaging member for engaging and holding the workpiece against the supporting surface. As such, the cited reference does not contain any position control devices nor does the reference discuss a process of use and application.
U.S. Pat. No. 6,553,644, issued Apr. 29, 2003, to Karmaniolas et al., discloses processing workpieces utilizing a frame and a fixture. The frame has a perimeter with an opening, and inner and outer side walls. A pair of shelves is located in the opening for supporting a workpiece and a spring retains the workpiece on the frame. The fixture has work locations with elevators that are moved by an elevator handle. The fixture also has an engagement handle for actuating the springs. The workpieces may be simultaneously mounted to or removed from the frames with the fixture. The frames are loaded into the locations and both handles are rotated to raise the elevators and bend the springs. The workpieces are then placed on top of the elevators and the elevator handle is rotated to lower the workpieces. Next, the engagement handle is rotated to release the springs to form assemblies that can be removed from the fixture. As such, the cited reference does not contain any substantive position control.
The above cited prior art does not disclose a suitable fixture for use during construction involving mounting a head window for a periscope system within a suitable frame. Consequently, those skilled in the art will appreciate the present invention that addresses the above and other problems.